I had the same issue with my 07 H3 stalling randomly on the highway and around town. A few weeks ago I drove it 200 miles, it lost power 5 times and it stalled twice all at highway speeds. I would have to throw it in neutral and restart it and throw it back in drive. I don't recommend doing this because I'm pretty sure that's why my tranny went last summer at 63k. So $2500 later and a rebuilt transmission I was still in the same boat. When it lost power and it came back on it's own, sometimes all the display lights would flash and the check engine light would stay on, other times only the security light would come on then go off. I've been chasing a ghost for 5 years. random codes: crankshaft position sensor-replaced it, air/fuel mixture, lost communication, air bag sensor, tpms, lean fuel. Once in a while it would it just wouldn't start. The engine would stay disabled but the door locks worked. The security light would flash when I tried to start it. I would try to manually do the door locks--nothing!! After 20-30 minutes of random attempts to start it and screwing with the key fob and door locks it would finally start. My headlights would dim every time I applied the brakes. I cleaned the throttle bodies and mass air flow sensor every six months. It didn't help. Long story short, I read the above posts and had my ECM replaced. That was 2 weeks ago. My H3 is doing great. So far it's problem solved. Well worth the $490. $390 for the ECM and $100 to program it. Thank you for this forum!!

I am glad it help!! I had the problem got lucky got pointers looked into it after replacing the ingnition switch! I tried to talk to gm and got nothing! Again I'm very glad it helped and I hope it helps others